A low-molecular microarray in which a various types of low-molecular compounds are introduced in trace quantities and fixed to a support, typically a glass slide, is useful as a tool for development of inhibitors for and functional analysis of proteins such as enzymes. However, in the conventional production processes of low-molecular microarrays, fixing of a low-molecular compound requires that all of the fixed low-molecular compounds have a functional group such as a hydroxyl or amino group. Therefore, it has only been possible to array a class of synthetic combinatorial library compounds (Non-patent reference No. 1). In a low-molecular compound, the part containing such a functional group in the structure of the compound faces toward the support on the binding side, and therefore has been of no use in protein-binding experiments on arrays. However, when a low-molecular compound is removed out from an array and then dissolved in a solvent, or when the compound before fixing to an array is dissolved in a buffer or the like, the possibility of the occurrence of interactions between that part of the low-molecular compound and indefinite proteins may arise, which has been thought to be a cause of adverse side reactions occurring during the development of pharmaceuticals.
On the other hand, it has been previously reported that a photoreactive compound can be used for fixing DNA molecules on a solid-phase support (Patent reference No. 1). It is considered that by applying this fixing technique to the production process for a low-molecular microarray, the problems inherent to the conventional low-molecular microarray production processes as stated above could be overcome. However, to date, there has been no report about the application of the above-described DNA-fixing process to the fixing of low-molecular compounds.    [Patent reference No. 1] Japanese Patent Application Laid-open No. 2001-178472    [Non-patent reference No. 1] MacBeath et al., J. Am. Chem. Soc., 1999, 121, 7967